/Engine/Source/Runtime/Engine/Public/AnimationRuntime.h
SourceWeightsIndices is used to index SourceWeights, to prevent caller having to supply an ordered weights array
static void BlendPosesTogether ( [TArrayView](API\Runtime\Core\Containers\TArrayView)< const [FCompactPose](API\Runtime\Engine\FCompactPose) > SourcePoses, [TArrayView](API\Runtime\Core\Containers\TArrayView)< const [FBlendedCurve](API\Runtime\Engine\Animation\FBlendedCurve) > SourceCurves, [TArrayView](API\Runtime\Core\Containers\TArrayView)< const float > SourceWeights, [TArrayView](API\Runtime\Core\Containers\TArrayView)< const int32 > SourceWeightsIndices, [FCompactPose](API\Runtime\Engine\FCompactPose) & ResultPose, [FBlendedCurve](API\Runtime\Engine\Animation\FBlendedCurve) & ResultCurve )